The human type I hair keratin subfamily comprises nine individual members, which can be subdivided into three groups. Group A (hHa1, hHa3-I, hHa3-II, hHa4) and B (hHa7, hHa8) each contains structurally related hair keratins, whereas group C members hHa2,
5α-reductase-IN-1 is a potent inhibitor of the enzyme 5α-reductase. This compound is primarily employed in research studies to investigate its potential efficacy in treating patterned alopecia. It is commonly used in combination with minoxidil, a well-known treatment for hair loss.